What to do with the old 520 Bridge pontoons?

SCOTT GUTIERRE, Seattle Post-Intelligencer

By SCOTT GUTIERREZ, SEATTLEPI.COM STAFF

Updated 8:44 pm, Sunday, September 23, 2012

Teams from 20 countries submitted their ideas on what to do with the old 520 Bridge's pontoons when the bridge is decommissioned. This entry would reuse the 520 pontoons as a floating mountain and wildlife habitat.

What about turning those massive pontoons into a water taxi system? Cyclists and pedestrians could use the pontoons to float around Seattle's gridlocked roadways.
Photo: Photos Provided By Sara Strouse.

What about turning those massive pontoons into a water taxi system?...

The old bridge as a park with gondolas? The 520 "Rethink Reuse" design competition received 73 entries from 20 countries.
Photo: Photos Provided By Sara Strouse.

The old bridge as a park with gondolas? The 520 "Rethink Reuse"...

This entry was called "Sea Quilt." Each pontoon would be given to a neighborhood as a floating park space. The pontoons could then be towed together to form a larger park as a symbol of community. The 520 "Rethink Reuse" design competition received 73 entries from 20 countries.
Photo: Photos Provided By Sara Strouse.

This entry was called "Sea Quilt." Each pontoon would be given to a...

This team had energy production in mind. They proposed using the pontoons to house turbines to harness tidal power.
Photo: Photos Provided By Sara Strouse.

This team had energy production in mind. They proposed using the...

One team proposed preserving the pontoons as a memorial to the old bridge. The 520 "Rethink Reuse" design competition received 73 entries from 20 countries.

One team proposed preserving the pontoons as a memorial to the old...

Photo: Photos Provided By Sara Strause.

This entry imagined transforming the pontoons into a floating cemetery and park on Lake Washington. According to the design poster, spreading of ashes would be allowed in designated gardens. The pontoons would be arranged "to create small tranquil inlets where acquatic gardens can flourish and filter the lakewater." As a urial psace, the gardens would provide a place for "biodegradeable urns to float until they descend to the bottom of the lake and nourish the local ecosystem."

Photo: Photos Provided By Sara Strause.

This entry imagined transforming the pontoons into a floating...

The winning entry, by David Dahl and Nicole Lew, both of Seattle, was called the "South Park Food Bridge." It would use the pontoons to reclaim the Duwamish waterfront in South Park. One set of pontoons would form parks with urban gardens and a boardwalk. The other set would be more porous and devoted to wetlands and creating habitat both above and below the water.

The state Route 520 Bridge and its 33 massive pontoons have floated on Lake Washington for 50 years. When the new bridge opens in 2014, something will have to be done with all that concrete.

Perhaps the state could find some ideas from a recent design competition, which asked for creative and innovative ideas about how the old bridge pontoons could be used without having to demolish them.

The "Rethink Reuse" design contest was part of architecture graduate student Sara Strouse's thesis project at Washington State University. A Kirkland native, she was inspired by the design competition that eventually led to an old elevated rail line in Manhattan being converted into The High Line Park. (That project was led by James Corner, the renowned landscape architect working on a vision for Seattle's post-viaduct waterfront.)

"If they could turn the High Line into such a beautiful park, I thought why couldn't we turn the 520 Bridge into something beautiful as well," Strouse said. "It just seemed like a waste not to at least consider the possibilities."

Current trends for the reuse of pontoons have been "floating docks, breakwaters and piers," but "what else could be done with such a feat of engineering?" the contest's website mused.

Each pontoon weighs about 9.5 million pounds and is as long as football field.

Many teams followed "The High Line" idea, and rendered designs of parks on top of the pontoons, including one in the form of the sea serpent known as "Kwakwaka'wakw," which is part of Pacific Northwest native mythology. One team proposed transforming the bridge into a floating farm with a farmer's market. One entry envisioned creating an eco-friendly residential and office space, and another saw the pontoons as building blocks for a tranquil, floating cemetery.

Judges were surprised by how many entries they received. The contest received 73 submissions from teams in 20 countries, including several from Seattle-area residents.

"A lot of us thought this was an obscure, somewhat local topic that would be interesting to a lot of local people. We did not expect to see such interest from all these places," said Shannon Nichol, one of the judges and a founding partner of Gustafson Guthrie Nichol, a landscape architecture firm. "And it was clear some people had never been to Seattle, and they had these ideas of what the city is about. That came through in some of the entries, which was fun to see."

You can browse some of the entries in the gallery above, including the winning submission. The winning team, David Dahl and Nicole Lew, of Seattle, was announced during a reception last Friday in South Lake Union.